configfile.c

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/*!
 ***********************************************************************
 * \file
 *    configfile.c
 * \brief
 *    Configuration handling.
 * \author
 *  Main contributors (see contributors.h for copyright, address and affiliation details)
 *    - Stephan Wenger           <[e-mail]>
 * \note
 *    In the future this module should hide the Parameters and offer only
 *    Functions for their access.  Modules which make frequent use of some parameters
 *    (e.g. picture size in macroblocks) are free to buffer them on local variables.
 *    This will not only avoid global variable and make the code more readable, but also
 *    speed it up.  It will also greatly facilitate future enhancements such as the
 *    handling of different picture sizes in the same sequence.                         \n
 *                                                                                      \n
 *    For now, everything is just copied to the inp_par structure (gulp)
 *
 **************************************************************************************
 * \par Configuration File Format
 **************************************************************************************
 * Format is line oriented, maximum of one parameter per line                           \n
 *                                                                                      \n
 * Lines have the following format:                                                     \n
 * <ParameterName> = <ParameterValue> # Comments \\n                                    \n
 * Whitespace is space and \\t
 * \par
 * <ParameterName> are the predefined names for Parameters and are case sensitive.
 *   See configfile.h for the definition of those names and their mapping to
 *   configinput->values.
 * \par
 * <ParameterValue> are either integers [0..9]* or strings.
 *   Integers must fit into the wordlengths, signed values are generally assumed.
 *   Strings containing no whitespace characters can be used directly.  Strings containing
 *   whitespace characters are to be inclosed in double quotes ("string with whitespace")
 *   The double quote character is forbidden (may want to implement something smarter here).
 * \par
 * Any Parameters whose ParameterName is undefined lead to the termination of the program
 * with an error message.
 *
 * \par Known bug/Shortcoming:
 *    zero-length strings (i.e. to signal an non-existing file
 *    have to be coded as "".
 *
 * \par Rules for using command files
 *                                                                                      \n
 * All Parameters are initially taken from DEFAULTCONFIGFILENAME, defined in configfile.h.
 * If an -f <config> parameter is present in the command line then this file is used to
 * update the defaults of DEFAULTCONFIGFILENAME.  There can be more than one -f parameters
 * present.  If -p <ParameterName = ParameterValue> parameters are present then these
 * overide the default and the additional config file's settings, and are themselfes
 * overridden by future -p parameters.  There must be whitespace between -f and -p commands
 * and their respecitive parameters
 ***********************************************************************
 */

#define INCLUDED_BY_CONFIGFILE_C

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>

#include "global.h"
#include "configfile.h"


static char *GetConfigFileContent (char *Filename);
static void ParseContent (char *buf, int bufsize);
static int ParameterNameToMapIndex (char *s);
static void PatchInp ();


#define MAX_ITEMS_TO_PARSE  10000


/*!
 ***********************************************************************
 * \brief
 *    Parse the command line parameters and read the config files.
 * \param ac
 *    number of command line parameters
 * \param av
 *    command line parameters
 ***********************************************************************
 */
void Configure (int ac, char *av[])
{
  char *content;
  int CLcount, ContentLen, NumberParams;

  memset (&configinput, 0, sizeof (InputParameters));
  // Process default config file

  printf ("Parsing Configfile %s", DEFAULTCONFIGFILENAME);
  content = GetConfigFileContent (DEFAULTCONFIGFILENAME);
  ParseContent (content, strlen(content));
  printf ("\n");
  free (content);

  // Parse the command line

  CLcount = 1;
  while (CLcount < ac)
  {
    if (0 == strncmp (av[CLcount], "-f", 2))  // A file parameter?
    {
      content = GetConfigFileContent (av[CLcount+1]);
      printf ("Parsing Configfile %s", av[CLcount+1]);
      ParseContent (content, strlen (content));
      printf ("\n");
      free (content);
      CLcount += 2;
    } else
    {
      if (0 == strncmp (av[CLcount], "-p", 2))  // A config change?
      {
        // Collect all data until next parameter (starting with -<x> (x is any character)),
        // put it into content, and parse content.

        CLcount++;
        ContentLen = 0;
        NumberParams = CLcount;

        // determine the necessary size for content
        while (NumberParams < ac && av[NumberParams][0] != '-')
          ContentLen += strlen (av[NumberParams++]);        // Space for all the strings
        ContentLen += 1000;                     // Additional 1000 bytes for spaces and \0s


        if ((content = malloc (ContentLen))==NULL) no_mem_exit("Configure: content");;
        content[0] = '\0';

        // concatenate all parameters itendified before

        while (CLcount < NumberParams)
        {
          char *source = &av[CLcount][0];
          char *destin = &content[strlen (content)];

          while (*source != '\0')
          {
            if (*source == '=')  // The Parser expects whitespace before and after '='
            {
              *destin++=' '; *destin++='='; *destin++=' ';  // Hence make sure we add it
            } else
              *destin++=*source;
            source++;
          }
          *destin = '\0';
          CLcount++;
        }
        printf ("Parsing command line string '%s'", content);
        ParseContent (content, strlen(content));
        free (content);
        printf ("\n");
      }
      else
      {
        snprintf (errortext, ET_SIZE, "Error in command line, ac %d, around string '%s', missing -f or -p parameters?", CLcount, av[CLcount]);
        error (errortext, 300);
      }
    }
  }
  printf ("\n");
}

/*!
 ***********************************************************************
 * \brief
 *    allocates memory buf, opens file Filename in f, reads contents into
 *    buf and returns buf
 * \param Filename
 *    name of config file
 ***********************************************************************
 */
char *GetConfigFileContent (char *Filename)
{
  unsigned FileSize;
  FILE *f;
  char *buf;

  if (NULL == (f = fopen (Filename, "r")))
  {
    snprintf (errortext, ET_SIZE, "Cannot open configuration file %s.\n", Filename);
    error (errortext, 300);
  }

  if (0 != fseek (f, 0, SEEK_END))
  {
    snprintf (errortext, ET_SIZE, "Cannot fseek in configuration file %s.\n", Filename);
    error (errortext, 300);
  }

  FileSize = ftell (f);
  if (FileSize < 0 || FileSize > 60000)
  {
    snprintf (errortext, ET_SIZE, "Unreasonable Filesize %d reported by ftell for configuration file %s.\n", FileSize, Filename);
    error (errortext, 300);
  }
  if (0 != fseek (f, 0, SEEK_SET))
  {
    snprintf (errortext, ET_SIZE, "Cannot fseek in configuration file %s.\n", Filename);
    error (errortext, 300);
  }

  if ((buf = malloc (FileSize + 1))==NULL) no_mem_exit("GetConfigFileContent: buf");

  // Note that ftell() gives us the file size as the file system sees it.  The actual file size,
  // as reported by fread() below will be often smaller due to CR/LF to CR conversion and/or
  // control characters after the dos EOF marker in the file.

  FileSize = fread (buf, 1, FileSize, f);
  buf[FileSize] = '\0';


  fclose (f);
  return buf;
}


/*!
 ***********************************************************************
 * \brief
 *    Parses the character array buf and writes global variable input, which is defined in
 *    configfile.h.  This hack will continue to be necessary to facilitate the addition of
 *    new parameters through the Map[] mechanism (Need compiler-generated addresses in map[]).
 * \param buf
 *    buffer to be parsed
 * \param bufsize
 *    buffer size of buffer
 ***********************************************************************
 */
void ParseContent (char *buf, int bufsize)
{

  char *items[MAX_ITEMS_TO_PARSE];
  int MapIdx;
  int item = 0;
  int InString = 0, InItem = 0;
  char *p = buf;
  char *bufend = &buf[bufsize];
  int IntContent;
  int i;

// Stage one: Generate an argc/argv-type list in items[], without comments and whitespace.
// This is context insensitive and could be done most easily with lex(1).

  while (p < bufend)
  {
    switch (*p)
    {
      case 13:
        p++;
        break;
      case '#':                 // Found comment
        *p = '\0';              // Replace '#' with '\0' in case of comment immediately following integer or string
        while (*p != '\n' && p < bufend)  // Skip till EOL or EOF, whichever comes first
          p++;
        InString = 0;
        InItem = 0;
        break;
      case '\n':
        InItem = 0;
        InString = 0;
        *p++='\0';
        break;
      case ' ':
      case '\t':              // Skip whitespace, leave state unchanged
        if (InString)
          p++;
        else
        {                     // Terminate non-strings once whitespace is found
          *p++ = '\0';
          InItem = 0;
        }
        break;

      case '"':               // Begin/End of String
        *p++ = '\0';
        if (!InString)
        {
          items[item++] = p;
          InItem = ~InItem;
        }
        else
          InItem = 0;
        InString = ~InString; // Toggle
        break;

      default:
        if (!InItem)
        {
          items[item++] = p;
          InItem = ~InItem;
        }
        p++;
    }
  }

  item--;

  for (i=0; i<item; i+= 3)
  {
    if (0 > (MapIdx = ParameterNameToMapIndex (items[i])))
    {
      snprintf (errortext, ET_SIZE, " Parsing error in config file: Parameter Name '%s' not recognized.", items[i]);
      error (errortext, 300);
    }
    if (strcmp ("=", items[i+1]))
    {
      snprintf (errortext, ET_SIZE, " Parsing error in config file: '=' expected as the second token in each line.");
      error (errortext, 300);
    }

    // Now interprete the Value, context sensitive...